Emulsion polymerization is a specific process of polymerization in which olefinically unsaturated monomers of low water solubility are emulsified in water by means of emulsifiers and are polymerized using water-soluble initiators such as, for example, potassium peroxodisulfate or redox initiators. Anionic and/or nonionic surfactants are the key constituents here. Via micelle construction in the aqueous solution, they ensure the process of emulsion polymerization.
Copolymerizable emulsifiers are in great demand in industry, since they are wholly or partly incorporated into the growing polymer chain and thus reduce, for example, the migration of free emulsifier molecules in the end application product. Copolymerizable emulsifiers occupy a middle position between monomers and conventional emulsifiers. In this position, they must be tailored to the monomer system used, in respect of their reactivity, and must not adversely alter the properties of the resultant polymer. At the same time, they must not lose their emulsificative properties as a result of the presence of a reactive group. On the basis of this combination of specific properties, there is a great demand on the part of industry for new copolymerizable emulsifiers.
German laid-open specification DE-A-10340081 describes copolymerizable surfactants of the formula HOOC—CH═CH—COO—(BO)z(PO)y(EO)xR1 in which R1 is an alkyl group or alkylphenol group having 8 to 24 carbon atoms, BO is a butylene oxide unit, PO is a propylene oxide unit, and EO is an ethylene oxide unit, and the numbers x, y, and z independently are 0 or numbers from 1 to 50, with the proviso that at least one of the numbers x, y, and z is other than 0, it being possible for the carboxyl group to be present partly or wholly in neutralized form and for the C═C double bond to have the cis or trans configuration.
Schoonbrood et al. in Macromolecules 1997 (30), 6024-6033 in table 1 (top of page 6025) describes an anionic surfactant “M14” for use as an emulsifier in emulsion polymerization, having the formula NaO4SC3H6OCOCH═CHCOOC14H29—which can also be written in the form NaO3SO—C3H6O—COCH═CHCOOC14H29.